Automatic product remover for paper cutting machine



Oct. 8, 1963 RQTHMAN f 3,106,119

AUTOMATIC PRODUCT REMOVER FOR PAPER CUTTING MACHINE- Filed July 13. 19603 Sheets-Sheet 1 I N V EN TORS l/ewev lfiJf/IMAIY BY 14 cm: $4547AUTOMATIC PRODUCT REMOVER FOR PAPER CUTTING MACHINE Filed July 15, 1.960

Oct. 8, 1963 H. ROTHMAN ETAL 3 Sheets-Sheet 2 INVENTORS Hemqy POrWMA YBy Age/we- Pas/rm W, %M, Wz izfi Oct. 8, 1963 RQTHMAN ETAL 3,106,119

AUTOMATIC PRODUCT REMOVER FOR PAPER CUTTING MACHINE Filed July 13, 19605 Sheets-Sheet 3 INVENTORS H6119) forum-w BY flew/E Pas/ m 7 71/1 4,@z/V? a 47 NEYS United States Patent 3,106,119 AUTOMATIC PRODUT REMOVERFOR PAPER CUTTING MACHTNE Henry Rothman, Larchrnont, N.Y., and ArchieRaskin, Englewood, NJ; said Raskin assignor to said Rothman Filed Italy13, 1961), Ser. No. 42,571 Claims. (Cl. (SS-82) This application relatesto a paper cutter having means for automatic ejection of the paper afterit has been cut and automatic control of the pressure bar that clampsthe paper in place to be cut.

Commercial paper cutters used to cut or trim stacks of paper are, bytheir very nature, dangerous devices to operate. The extent of thedanger involved in using them is indicated by the fact that it has beenhound necessary to pass strict legislation requiring that certainstandards of safety be met in the design of these devices. One of themost critical times in each cycle of operation of such cutters is afterthe paper has been cut or trimmed when it is necessary to unclamp theremaining paper and to remove it from the cutter. This requires theoperator to place his hands directly beneath the blade and the pressurebar in order to grasp the paper.

One of the Objects of the present invention is to provide for automaticejection of paper after it has been trimmed or out. In addition, theinvention provides a controlled sequence of clamping and ejecting thepaper under the control of interconnected limit switches.

The invention comprises basically a paper cutter having a horizontalbase or bed, a vertically movable pressure bar suspended over the bedand guided by vertical posts at the side of the bed, a suitable knifeblade, and a horizontally slidable back gauge mounted on the bed in sucha way that it can be positioned at any desired distance behind thepres-sure bar. The front face of the back gauge is serrated and theteeth of a rakelike ram lit within the serrations. The ram is providedwith a handle which extends to the rear of the bed and is movedhorizontally back and forth between certain limits by means of anactuator. At the rearward limit, the teeth of the ram are completelywithin the serrations of the back gauge, so that only the front surfaceof the serrations is contacted by the paper to be cut. After the paperhas been cut, the ram is moved forwa-ud to the other limit, at which theteeth are beyond the location of the knife so that the paper may beremoved from the cutter without the necessity of the operators everplacing his hands beneath the knife.

At or near the limits of travel of the ram, limit switches are engagedwhich control the actuator. These limit switches are interconnected in acircuit with additional limit switches that make contact with thepres-sure bar, the whole operation being such as to permit the ram tomove forward toward the pressure bar at the forward end of the cutteronly when the pressure bar is in its upward position. I

The invention will be described in greater detail in connection with thedrawings, in which:

FIG. 1 shows a partial perspective view of the top of part of a papercutter constructed according to the invention;

FIG. 2 shows the circuit incorporating the limit switches that controlthe operation of the pressure bar and the ram; 7

FIG. 3 is a partial side view of the paper cutter 0 FIG. 1 with the ramin the extended forward position.

FIG. 4 shows a ditierent embodiment of the actuator for the paper cutterof FIG. 1; and

FIG. 5 shows still another form of actuator.

Referring to FIG. 1, the cutter has a fiat bed or base 11 with a pair ofvertical guide posts 12. and13, one on each side of the base. A pressurebar 14 slides in grooves 16 and 17 in the guide posts 12 and 13,respectively, and is provided with a number of projections 18 extendingtoward the rear of the cutter to distribute pressure over a Wider areaof the paper. The paper itself is inserted into the cutter in stacks, asindicated by reference character 1?, and is pushed toward the rear ofthe cutter until it comes up against a back gauge 21.

The back gauge 21 is a substantial member with a serrated fnont surface22 perfectly aligned with the knife blade 23 of the cutter so that thestack of paper 19 may be cut perfectly square. The knife blade 23 may besupported and operated in nny conventional fashion. As shown here, itmoves in a pair of grooves 24 and 26 in the guide posts 12 and 13,respectively, and operates in the manner of a guillotine.

The elements which have been described so far are standard elements,found in more or less the same form in commercial paper cutterspresently available. In addition to these elements, the presentinvention includes further means to make possible automatic operation ofthe paper cutter, particularly the ejection of stacks of cut paper.These means provide for automatic interrelated operation of the pressurebar 14 together with automatic ejection of the paper.

The pressure bar 14 is raised and lowered by means of a fluid-operatedcylinder 27. The fluid to operate the cylinder may be either hydraulicfluid or air and is supplied to the cylinder through one or the other oftwo fluid lines 2.9 and 31. This is a conventional fluidoperatedcylinder with an internal piston (not shown) connected by a connectingrod 32 to the pressure bar 14. The valve means for controlling the fluidflow to one or the other of the lines 29 and 31 may be conventional andneed not be described in detail. It is sufiicient to note that when itis desired to raise the pressure bar 14, the fluid is admitted throughthe line 31 to the lower side of the enclosed piston within the cylinder27 and withdrawn from the upper side of the cylinder 27 by way of theupper line 29. Conversely, when it is desired to push the pressure bar14 down against a stack of paper 19, the fluid is admitted via line '29to the upper portion of the cylinder 2''] and withdrawn through the line31 of the lower portion. The degree of pressure applied to the pressurebar 14 by the fluid-operated cylinder 27 is quite suificient to hold astack of paper 19 in place and may be varied as desired. When thepressure bar 14- is at the upper limit of its field of travel, itactuates the arm of a limit switch 33, and when it is at the lower endof its range of travel and down against a stack of paper 19, it actuatesa lower limit switch 34. As a matter of fact, the limit switch 33 may belocated where it can be actuated by either of the veitically movingmembers, the knife blade 23 or the pressure bar 14, at the upper part ofthe range of travel of the vertically moving member. These switches areinterconnected in a circuit which will be described hereinafter.

The means for ejecting a stack of paper 19 from the cutter after thepaper has been cut or trimmed includes a ram 36 which is somewhatsimilar to a garden rake and is provided with downwardly extending teeth37 that fit into the serrations in the front side 22 of the back gauge21. The cam 36 has a handle, or pusher, 38 extending to the rear andsupported in two journals 39' and 41. Motive power to force the ramforward in order to eject a stack of paper 19 from the cutter issupplied by means of a ram actuator 42 which may be an electric motoror, as will be described hereinafter, other suitable motive means. Inthe case of an electric motor, the actuator 42 has an output shaft 43which is connected through a crank arm 44 to a connecting rod 46. Theconnecting rod 46, in turn, is connected by means of a pivot block 47 tothe pusher rod 38, so as to supply force to move the ram 36 back andforth. At the forward end of its range of travel the block 47, which isrigidly attached to the bar 38, actuates a forward limit switch 48 andat the rear extreme of its range of travel the block 47 actuates anotherlimit switch 49. The journals 39 and 41 in which the bar 38 rides andthe actuator 42, together with the limit switches 43 and 49, are allmounted on a support bracket or plate 51 which is attached by means ofbolts 52 and 53 to the back gauge 21 to move therewith. In this way, itmay be assured that the ram 35 will, at the rear of its range of travel,always be retracted sufiiciently to make the teeth 37 come within theserrations in the front side of the back gauge 21. As a result, only thefront surface 22 of the back gauge 21 will be in contact with the paper19' during the time that the paper is in the cutter, and the teeth 37 ofthe ram 36 will contact the paper 19 only during such time as the paperis being ejected from the cutter. This permits the location of cut to bedetermined very accurately by the precise distance between the knifeblade 23 and the front surface 22 of the back gauge 21, and there is noneed to be as accurate in the manufacture of the ram 36 or the insertionof its teeth 37.

The operation of the cutter of FIG. 1 will be de scribed with referenceto the electrical circuit of FIG. 2. At the beginning of a cycle ofoperation the pressure bar 1 and the knife blade 23 are at the tops oftheir ranges of travel so as to leave space for a stack of paper to beinserted between the guide posts 12 and i3 and pushed against the backgauge 21. In order to permit the paper to be pushed all the way againstthe back gauge 21. In order to permit the paper to be pushed all the wayagainst the front surface 2-2 of the back gauge, the ram must be at therear of its range of travel which means that the block 47 will beagainst the limit switch 49. As indicated in FIG. 2, this limit switchis normally closed and, therefore, being actuated by the block 47 meansthat it is in the open state at the beginning of the cycle.

After the paper 19 has been pushed into place, the cylinder 27 isactuated to bring the pressure bar 14 down against the paper. This isaccomplished by directing pressure fluid into the upper line 29' andwithdrawing it from the lower line 31. In moving down the pressure bar14 actuates the lower limit switch 34. This switch is of thenormally-open type, and actuating it closes it.

The limit switch 34 is connected to one of a pair of electrical supplylines 52 and 53 which may either be an ordinary single-phase line or twolines of a threephase circuit. The switch 34 is further connected inseries with the coil of a relay 54. This relay is provided with anormally-closed contact 54a and a normally-open contact 54b. In theunenergized state of the relay the movable contact 54a is closed inseries with the power supply line 53. The coil of the relay 54 isenergized from the lines 52 and 53 by way of the switch 34 and henormally-closed contacts Immediately upon being energized when thepressure bar closes the switch 34, the relay 54; moves the arms of thecontact pairs 54a and 54b to their alternative positions. Thealternative position of the arm of contacts 54a is against a contact Ste which is connected to a line 56 which in turn is connected to oneterminal of the coil of the relay 57 and to normally-closed contacts 58aof a relay 58. Relay 58 is, at this time, not energized, because theblock 4'7 is pressing against the normally-closed switch 49, holding itopen. In the unenergized state of the relay 58, the contacts 58a form aclosed circuit with the power supply line 53. As a result, when therelay 54 is energized and the arm of contacts 54a moves to the energizedposition, the relay 54 remains energized because it then derives currentfrom the line 53 by way of the line 56 and the normally-closed contacts58a of the relay 58. Furthermore, the energized position of thenormally-open contacts 54b completes a circuit directly to the powersupply line 52. Since the movable arm of the contacts 54-12 is alsoconnected to the junction between the switch 3 and the coil of the relay54, the relay 54 remains energized even'after the pressure bar 14 movesup and out of contact with the switch 34.

The reason that the pressure bar 14 moves up away from the switch 34 andaway from the paper 19 is that fluid in the cylinder 27 has been removedby way of the upper line 29 and has been supplied to the lower end ofthe cylinder by way of the line 31. Again, this part of the operation isstandard and not part of the present invention.

As a result of the release of pressure on the stack of paper 19 when thepressure bar 14 moves up, the paper is free to be ejected from thecutter. This occurs when the pressure bar 14 moves up into contact withthe arm of the upper limit switch 23. As shown in FIG. 2, the limitswitch 33a is connected in series with the contacts 54!), which are nowclosed, so that the switch 33 is directly connected to the supply line52. Thus, when the pressure bar 14 moves up and actuates the switch 33,the relay 57 is energized from lines 52 and 53 via switches 33 and 48and the normally-closed contacts 58a. When the relay 57 is actuated itcloses the normally open contacts 57b and 57c at the same time that itopens the normally closed contacts 57a. The contacts 57b and 57c areconnected in series between the power supply lines 52 and 53 and anactuator control 42 This control energizes the actuator 42 of FIG. 1 tocause it to push the ram 36 forward so as to eject the stack of paper 19from the cutter. If the actuator 42 is a motor the control circuit 42ftherefor may be simply the field windings of the motor connected so asto cause the motor to operate in one direction.

The actuator control circuit 42f remains energized so long as the relay57 is energized which in turn is governed by the normally closed limitswitch 48. As soon as the ram reaches its forwardmost position at whichthe block 47 engages the limit switch 4-8, the latter opens up therebyopening the circuit through which the relay 57 is energized. As a resultthe relay 57 becomes deenergized and the normally open contacts 5% and570 open up thereby de-energizing the forward actuator control circuit42 At the time that the ram 36 starts forward the block 47 moves awayfrom the rear limit switch 49 thereby allowing the latter to return toits normally closed condition. However, the relay 58 which is in serieswith the limit switch 49 is not immediately energized because at thistime the relay 57 is energized and the normally closed contacts 57a areopen. It is only after the block 47 engages the forward limit switch 48and opens it up so as to allow the relay 57 to become de-energized thatthe normally closed contacts 57a can return to their closed state andpermit the relay 58 to be energized by a circuit including the normallyclosed limit switch 49, and the normally closed contacts 57a. Energizingthe relay 58 causes the normally open contacts 58b and 58c to close.These contacts are in series with the power supply lines 52 and 53 and areverse-control 421* for the actuator 42. Again, in the event that theactuator is an electric motor, the reverse-control 42r may simply be thefield windings of the motor connected to cause the motor to rotate inthe reverse direction. This places the circuit and the cutter back inits original condition ready to receive a new load of paper.

FIG. 3 shows a partial side view of the cutter of FIG. 1 with some ofthe parts broken away to show the interior. Part of the bed 11 is brokenaway to show a a feed arrangement for adjusting the position of the backgauge 21. This feed arrangement consists of a feed screw 61 cooperatingwith a threaded member 62. This threaded member rides upon a guide bar63 and is actually the base of the back gauge 21. Rotating the feedscrew 61 by means of a handle which is of the custom-ary type and is notshown, causes the threaded member 62, to move backward or forwarddepending upon the direction of rotation of the screw and thus bring theback gauge 21 closer to or farther from the knife blade 23.

FIG. 3 also shows the mounting of the plate 51 on the back gauge 21. Inthe condition shown in FIG. 3, the ram 36 is advanced to its forwardmostposition and the connecting arm 46 is directly in line with the crankarm44. As may be seen, in this condition the stack of paper 19 has beenpushed completely out from under the knife blade 23 so that there is nonecessity for the operators getting his hands under the blade or underthe pressure arm 44 to the connecting rod 46 travels along a circularpath indicated by the arc 66. Because of this inerrant oscillatingmotion, due to the circular path, it is not necessary for the directionof the rotation of the shaft 43 to be reversed; the actuator couldsimply be permitted to continue in one direction until the block 47returned to the rear limit switch 49 arid de-energized the actuator.

FlG. 4 shows a different type of actuator. In this figure the actuatoris a fluid-operated cylinder which may be either operated by air or byhydraulic pressure. The cylinder is indicated by reference character 142and has fluid lines 67 and 68 connected to opposite ends of the cylinderin the customary fashion to cause the piston (not shown) within thecylinder 142 to move either to the left or to the right. This piston isdirectly connected to the rod 138 which corresponds to the rod 38 ofFIGS. 1 and 3 and so pushes the ram 36 or pulls it as required. Thefluid pressure supplied to one or the other of the lines 67 andcfi iscontrolled by the customary solenoid operated valve 69. This is afour-way valve which either supplies fluid pressure to the lines 67 andwithdraws it at the same time from the lines 68 so as to move the ram 36to the left or reverses the foregoing condition and supplies pressure tothe lines 68 and withdraws it from the lines 67 to cause the ram 36 toreturn to the right to its plam within the serrated portion of the b ackgauge 21. In the case of a solenoid operated valve system such as thisthe forward control circuit 42 of FIG. 2 may be one of the valvesolenoids and the reverse oontrol circuit 42; may be the other sincethere are normally two.

FIG. 5 shows still another modification of the actuator arrangement. Inthis case a bracket 71 is mounted on the back gauge 21 and is providedwith two threaded upright members 72 and 73. A long feed screw 74 whichtakes the place of the rod 38 of FIGS. 1 and 3, is threaded through theuprights 72 and 73 and is connected to the ram 36 at its forward end. Agear 76 is aifixed to the feed screw 74 so that when the gear rotatesthe feed screw rotates with it. The gear is connected by means of aninternally toothed rfeed belt 77 to another gear '73 on the shaft of amotor 242.

When the motor 242 is energized by the forward control circuit 42 toturn in one direction, the gear 78 turns with the shaft of the motorcausing the belt 77 to turn with it and thereby to turn the lower gear'76. This in turn rotates the feed screw 74 which moves forward in thethreaded uprights 72 and 73 to push the ram 36 to the left. Conversely,when the direction of rotation of the motor 242 is reversed the gear 78and the belt 77 are driven in a reversed direction driving the lowergear 76 in reverse direction and causing the feed screw 74 to return toits original position.

While the invention has been described in terms of certain specificembodiments it will be recognized by those skilled in the art thatmodifications may be made therein which will still be within the scopeof the following claims.

What is claimed is:

1. A paper cutter comprising a base; a pressure bar perpendicularlymovable with respect to said base; a knife located adjacent to saidpressure bar and movable to cut the paper disposed on said base, meansto drive said pressure bar and knife substantially simultaneouslythrough an upper and lower region of travel; a back gauge on said base;a ram; an actuator for said ram fixedly mounted with respect to saidback gauge, said actuator having controllably movable means connected tosaid ram to move said ram longitudinally along said base from said backgauge to a more forward location and to return said ram to a rearwardlocation adjacent to said back gauge; a first limit switch located to beactuated by said pressure bar when said pressure bar is at the upperregion of its range of travel; a second limit switch located to beactuated by said pressure bar when said pressure bar is at its lowerregion of its range of travel; a third limit switch located to beactuated when said ram is in the forward portion of its range of travel;a fourth limit switch located to be actuated when said ram is in therearward region of its range of travel, and a circuit connecting saidlimit switches and said ram actuator whereby said actuator is energizedwhen said first limit switch is actuated after said second limit switchhas been actuated so as to push the ram forward to eject paper from saidcutter, and said third limit switch is actuated when said ram is in theforward position to reverse the movement of said actuator to return saidram to the rearward position.

2. A paper cutter comprising a base; a pressure bar perpendicularlymovable with respect to saidbase; a knife located adjacent to saidpressure bar and movable to cut the paper disposed on said base, meansto drive said pressure bar and knife substantially simultaneouslythrough an upper and lower region of travel; a back gauge movablymounted on said base; a ram; an electric motor actuator for said ramfixedly mounted with respect to said back gauge to move therewith;movable means connecting the shaft of said motor to said ram to movesaid ram longitudinally along said base fromsaid back gauge to a moreforward location and to return said ram to a rearward location adjacentto said back gauge; a first limit switch located to be actuated by saidpressure bar when said pressure bar is at the upper region of its rangeof travel; a second limit switch located to be actuated by said pressurebar when said pressure bar is at its lower region of its range oftravel; a third limit switch located to be actuated when said ram is inthe rearward region of its range of travel, and a circuit connectingsaid limit switches land said motor whereby said motor is energized whensaid first limit switch is actuated after said second limit switch hasbeen actuated so as to push the ram forward to eject paper from saidcutter, and said third limit switch is actuated when said ram is in therearward position to halt the operation of said motor when said ramreturns to the rearward position after ejecting the paper.

3. A paper cutter comprising a base; a pair oif vertically movingmembers, one of said members being a pressure bar perpendicularlymovable with respect to said base, the other of said members being aknife located adjacent to said pressure bar and movable to cut the paperdisposed on said base, means to drive said pressure bar and kru'fesubstantially simultaneously through an upper and lower region oftravel; :a back gauge movably mounted on said base; a ram; a reversiblemotor actuator for said ram fixedly mounted on said back gauge to movetherewith; a crank arm and a connecting rod connecting the shaft of saidmotor to said ram to move said ram longitudinally along said base fromsaid back gauge to a more forward location and to return said ram to arearward location adjacent to said back gauge; a first limit switchlocated to be actuated by one of said vertically moving members whensaid one of said vertically moving members is at the upper region of itsrange of travel; a second iimit switch located to be actuated by saidpressure bar when said pressure bar is at its lower region of its rangeof travel; a third limit switch located to be actuated when said rain isin the forward portion of its range of travel; a fourth limit switchlocated to be actuated when said ram is in the rearward region of itsrange of travel, and a circuit connecting said limit switches and saidmotor whereby said motor is energized when said first limit switch isactuated after said second limit switch hast been actuated so as to pushthe ram forward to eject paper from said cutter, and said third limitswitch is, actuated when said ram is in the forward position to reversesaid motor to return said ram to the rearward position.

4. A paper cutter comprising a base; a pressure bar perpendicularlymovable with respect to said base; a knife located adjacent to saidpressure bar and movable to cut the paper disposed on said base, meansto drive said pressure bar and knife substantially simultaneouslythrough an upper and lower region of travel; a back gauge movablymounted on said base and having a serrated face; a ram having areversible motor actuator for said ram fixedly mounted with respect tosaid back gauge to move therewith; a crank arm and a connecting rodconnecting the shaft of said motor to said ram to move said ramlongitudinally along said base from said back gauge to a more forwardlocation and to return said ram, to a rearward location with said Iusher means fitting within said serrated face; a first limit switchlocated to be actuated by said pressure bar when said pressure bar is atthe upper region of its range of travel; a second limit switch locatedto :be actuated by said pressure bar when said pressure bar is at itslower region of its range of travel; a third limit switch located to beactuated when said ram is in the forward portion of its range of travel;a fourth limit switch located to be actuated when said ram is in therearward region of its range of travel, and a circuit connecting saidlimit switches and said motor whereby said motor is energized when saidfirst limit switch is actuated after said second limit switch has beenactuated so as to push the ram forward to eject paper from said cutter,and said third limit switch is actuated when said ram is in the forwardposition to reverse said motor to return said ram to the rearwardposition.

5. A paper cutter comprising a base; a pressure bar perpendicularlymovable with respect to said base; a knife located adjacent to saidpressure .bar and movable to cut the paper disposed on said base, meansto drive said pres.- sure bar and knife substantially simultaneouslythrough an upper and lower region of travel; a back gauge movablymounted on said base; a ram; a reversible motor actuator for said ramfixedly mounted on said back gauge to move therewith; a crank arm and aconnecting rod connecting the shaft of said motor to said ram to movesaid ram longitudinal ly along said base from said back gauge to a moreforward location and to return said rarn to a rearward location adjacentto said back gauge; a first limit switch located to be actuated by saidknife when said knife is at the upper region of its range of travel; asecond limit switch located to be actuated by said pressure bar whensaid pressure bar is at its lower region of its range of travel; a thirdlimit switch located to be actuated when said ram is in the forwardportion of its range of travel; a fourth limit switch located to beactuated when said ram is in the rearward region of its range of travel,and a circuit connecting said limit switches and said motor whereby saidmotor is energized when said first limit switch is actuated after saidsecond limit switch has been actuated so as to push the ram forward toeject paper from said cutter, and said tird limit switch is actuatedwhen said ram is in the forward position to reverse said motor to returnsaid ram to the rearward position.

References Cited in the file of this patent UNITED STATES PATENTS947,360 Wallenthin Ian. 25, 1910 1,653,303 Mulroney Dec. 20, 19272,009,487 Ernst July 30, 1935 2,259,576 MacMillin Oct. 21, 19412,613,592 Nemir Oct. 14, 1952 2,752,847 Vandenburgh July 3, 1956 FOREIGNPATENTS 13,398 Great Britain Oct. 4, 1887 838,740 Germany May 12, 1952

5. A PAPER CUTTER COMPRISING A BASE; A PRESSURE BAR PERPENDICULARLYMOVABLE WITH RESPECT TO SAID BASE; A KNIFE LOCATED ADJACENT TO SAIDPRESSURE BAR AND MOVABLE TO CUT THE PAPER DISPOSED ON SAID BASE, MEANSTO DRIVE SAID PRESSURE BAR AND KNIFE SUBSTANTIALLY SIMULTANEOUSLYTHROUGH AN UPPER AND LOWER REGION OF TRAVEL; A BACK GAUGE MOVABLYMOUNTED ON SAID BASE; A RAM; A REVERSIBLE MOTOR ACTUATOR FOR SAID RAMFIXEDLY MOUNTED ON SAID BACK GUAGE TO MOVE THEREWITH; A CRANK ARM AND ACONNECTING ROD CONNECTING THE SHAFT OF SAID MOTOR TO SAID RAM TO MOVESAID RAM LONGITUDINALLY ALONG SAID BASE FROM SAID BACK GAUGE TO A MOREFORWARD LOCATION AND TO RETURN SAID RAM TO A REARWARD LOCATION ADJACENTTO SAID BACK GAUGE; A FIRST LIMIT SWITCH LOCATED TO BE ACTUATED BY SAIDKNIFE WHEN SAID KNIFE IS AT THE UPPER REGION OF ITS RANGE OF TRAVEL; ASECOND LIMIT SWITCH LOCATED TO BE ACTUATED BY SAID PRESSURE BAR WHENSAID PRESSURE BAR IS AT ITS LOWER REGION OF ITS RANGE OF TRAVEL; A THIRDLIMIT SWITCH LOCATED TO BE ACTUATED WHEN SAID RAM IS IN THE FORWARDPORTION OF ITS RANGE OF TRAVEL; A FORTH LIMIT SWITCH LOCATED TO BEACTUATED WHEN SAID RAM IS IN THE REARWARD REGION OF ITS RANGE OF TRAVEL,AND A CIRCUIT CONNECTING SAID LIMIT SWITCHES AND SAID MOTOR WHEREBY SAIDMOTOR IS ENER-